docs: def get_keystone_manager_from_identity_service_context():
      """Return a keystonmanager generated from a
      instance of charmhelpers.contrib.openstack.context.IdentityServiceContext
      @returns keystonamenager instance
     """
      context = IdentityServiceContext()()
      if not context:
          msg = "Identity service context cannot be generated"
          log(msg, level=ERROR)
          raise ValueError(msg)
  
      endpoint = format_endpoint(context['service_protocol'],
                                 context['service_host'],
                                 context['service_port'],
                                 context['api_version'])
  
      if context['api_version'] in (2, "2.0"):
          api_version = 2
      else:
          api_version = 3
  
      return get_keystone_manager(endpoint, api_version,
                                  username=context['admin_user'],
                                  password=context['admin_password'],
                                  tenant_name=context['admin_tenant_name'])